Consider the following data - feel free to play around with the SQL queries yourself (Links at the bottom)

    Average number of ______ by site

                        upvotes/question    upvotes/user        answers/question        answers/user
    Unix&Linux          8.71                5.19                3.05                    1.81
    Stackoverflow       6.38                12.76               3.17                    6.34
    AskUbuntu           6.34                3.93                2.61                    1.62
    Linguistics         8.74                4.74                3.25                    1.76
    Superuser           6.45                4.47                2.98                    2.06

My reading of the story is not upvotes in general, more like upvotes in the context of the overall userbase. Fewer of us answer fewer questions than any of the other 4 communities I picked on a whim. Not only that, but we seem to reward questions less than the other communities. If I was to make a rash judgement, I'd say we prefer to just harvest what the community has to offer but feel less inclined to contribute and to reward those who contributed.

https://data.stackexchange.com/superuser/query/614178/answers-per-user
https://data.stackexchange.com/superuser/query/614175/answers-per-question
https://data.stackexchange.com/superuser/query/614068/upvotes-per-user
https://data.stackexchange.com/superuser/query/613862/number-of-upvotes-per-post

PS: I am tempted to make a few more queries - if you have one in mind, let us know in the comments and I'll see to it that I find the time to run the best ones as an update to this.

Update 20170113
This is what voter ranges look like on AskUbuntu:

    	The number of users in the entire community: 	   404632
    +-------------------------------------------------------------------------------------------+
      Number of users who never voted: 			         	   328852	    81.27%
      Number of users who upvoted between 	0	-	5: 	        45342	    11.21%
      Number of users who upvoted between 	5	-	10: 	    10825	     2.68%
      Number of users who upvoted between 	10	-	20: 	     8255	     2.04%
      Number of users who upvoted between 	20	-	40: 	     5453	     1.35%
      Number of users who upvoted between 	40	-	80: 	     3148	     0.78%
      Number of users who upvoted between 	80	-	160: 	     1535	     0.38%
      Number of users who upvoted between 	160	-	320: 	      635	     0.16%
      Number of users who upvoted between 	320	-	640: 	      322	     0.08%
      Number of users who voted more: 			         	      113	     0.03%

And this is what Stack Overflow looks like close up and personal:

    	The number of users in the entire community: 	  6539900
    +-------------------------------------------------------------------------------------------+
      Number of users who never voted: 		         		  5594471	    85.54%
      Number of users who upvoted between 	0	-	5: 	       331193	     5.06%
      Number of users who upvoted between 	5	-	10: 	   126725	     1.94%
      Number of users who upvoted between 	10	-	20: 	   125488	     1.92%
      Number of users who upvoted between 	20	-	40: 	   109279	     1.67%
      Number of users who upvoted between 	40	-	80: 	    87916	     1.34%
      Number of users who upvoted between 	80	-	160: 	    65310	     1.00%
      Number of users who upvoted between 	160	-	320: 	    43647	     0.67%
      Number of users who upvoted between 	320	-	640: 	    28872	     0.44%
      Number of users who voted more: 			         	    10490	     0.16%

You can experiment with the numbers at: https://data.stackexchange.com/askubuntu/query/615470/upvotes-per-user-ranges

The query is pretty easy to tune to your liking.