Shooting data from here covers years 2013-2015 (as of this writing). If you pair it with 2014 population data from this .csv file, you can get an idea of the daily risk of dying or being wounded in a mass shooting across the US, by state, as shown below:

There are 4 states that did not have a mass shooting since at least 2012. They are Hawaii, New Hampshire, North Dakota and Wyoming.

The impetus for this came from this WonkBlog post. A headline that points out that so far this year there have been more mass shootings than days will get anybody’s attention. After one agrees that things are indeed bad, a fair question might be whether they’re getting worse.

The evidence of that is mixed. Translated to daily risk (as approximated by incidence of the dead and wounded per 100M person-days), this year is worse than 2014, about as bad as 2013 for the risk of dying, and worse for the risk of getting wounded:

year days population dead wounded dead_incidence_100M wounded_incidence_100M
2013 365 318335444 502 1266 0.43 1.09
2014 365 318335444 383 1251 0.33 1.08
2015 274 318335444 375 1089 0.43 1.25

The numbers in the table above take the 2014 US population as baseline. If this population is higher in 2015 than it was in 2014, then the risks estimated on the bottom row of this table will be slightly lower, but this should be close enough for a rough idea. The code is on GitHub.