During the era of CPU mining is wasn't unusual for miners to search only the lower part of the nonce range. since a full 2^32 search would take too much time.
I haven't analyzed the data yet, but I suspect there are more low nonces than high ones.
$ cat nonce.lst | grep "^0" | wc
47080 94160 753333
$ cat nonce.lst | grep "^1" | wc
12470 24940 201587
$ cat nonce.lst | grep "^2" | wc
7442 14884 121209
$ cat nonce.lst | grep "^3" | wc
6314 12628 103299
$ cat nonce.lst | grep "^4" | wc
6106 12212 99962
$ cat nonce.lst | grep "^5" | wc
6127 12254 100398
$ cat nonce.lst | grep "^6" | wc
6086 12172 99695
$ cat nonce.lst | grep "^7" | wc
6077 12154 99477
$ cat nonce.lst | grep "^8" | wc
5895 11790 96551
$ cat nonce.lst | grep "^9" | wc
5908 11816 96690
$ cat nonce.lst | grep "^a" | wc
5833 11666 95570
$ cat nonce.lst | grep "^b" | wc
5899 11798 96666
$ cat nonce.lst | grep "^c" | wc
5994 11988 98234
$ cat nonce.lst | grep "^d" | wc
5898 11796 96569
$ cat nonce.lst | grep "^e" | wc
5872 11744 96231
$ cat nonce.lst | grep "^f" | wc
5815 11630 95291
For those of you that don't speak Unix, the above data shows I'm correct.