2017-07-22  https://www.cms.gov/Research-Statistics-Data-and-Systems/Downloadable-Public-Use-Files/Provider-of-Services/Downloads/CLIA_Data_Issues_Alert.pdf  

2015-05-23 2011-2014 posCCYY data fiels updated so that string variables are string and 
           variables like state codes, county codes, ZIP Code, and the like have leading zeros.

2015-05-23 1984-1990 files updated to have string state and county codes