Shouldn't difficulty increase as time goes on?
It usually does, but not always...in a year it has gone from 377... to 1445...:
Aug 02 2016 201,893,210,853 -5.43% 1,445,207,896 GH/s
Jul 18 2016 213,492,501,108 0.04% 1,528,238,850 GH/s
Jul 04 2016 213,398,925,331 1.88% 1,527,569,009 GH/s
Jun 21 2016 209,453,158,595 6.83% 1,499,324,110 GH/s
Jun 08 2016 196,061,423,940 -1.63% 1,403,462,340 GH/s
May 24 2016 199,312,067,531 2.60% 1,426,731,353 GH/s
May 11 2016 194,254,820,283 8.73% 1,390,530,167 GH/s
Apr 28 2016 178,659,257,773 -0.01% 1,278,892,782 GH/s
...
Dec 31 2015 103,880,340,815 11.16% 743,604,444 GH/s
...
Aug 22 2015 54,256,630,328 2.95% 388,384,088 GH/s
Aug 08 2015 52,699,842,409 0.81% 377,240,166 GH/s
...
Oct 23 2014 35,985,640,265 2.81% 257,595,247 GH/s
See
https://bitcoinwisdom.com/bitcoin/difficultyamong other places