Trust in the general population declined from 48.1% in 1972 to 31.9% in 2014. Over the same period of time, trust among whites fell from 54.7% to 39.3%, a trajectory modestly gentler than that of the population taken as a whole.
Parenthetically, there is a precipitous decline in 1983 followed by a rebound in 1984 that mirrors the data for the entire population, a variance probably explained by a transcription issue with the results or simply sampling noise. It's tempting to combine the years for a smoothed average that meshes better with the rest of the data, but I've never massaged the numbers here before and I'm not about to start doing so now, so make of it what you will.
GSS variables used: YEAR, TRUST(1-2), ETHNIC(2-4,6-15,18,19,21,23-27,32,33,35,36,41,97)