Major update: national ENPA opt-in, analysis of exposure characteristics, 14 day metrics,

Lots of updates. Major changes:

• Use national ENPA opt-in rather than regional ENPA opt-in calculated from comparing verified codes ENPA/ENCV data. The people who verify codes are not entirely representative of the entire ENPA population, so this gives a more representative estimate, although it doesn't take into account possible regional variables in opt-in %'s. But looking at a few states, it also seems to reflect what is happening overall in terms of ENX adoption.
• added analysis based on the userRisk and userRiskParameters metrics, that show data such as the percent of exposures that had a sumScore > 120 minutes, and the percent of exposure that occurred at less than 60 dB of attenuation.
• analysis of the 14 day metrics, which provide a higher signal to noise ratio, and also better separates out report type.