CNA Cert

when did it become mandatory for Nursing Assistants to be Certified?
I became certified in 94 and I know that back in the 80's alot of the CNA's then weren't certified because it wasn't required.
My mother in law was trying to tell me that when she was a CNA that she was certified and was also trained in foley cath insertion. When I worked at the hosp they trained us in foley cath insertion, but it was never part of out cert nursing assistant training, it was thru the hosp.
My mother in law was a CNA in the early to mid 80's.