Hi Carole
In Spanish, like in English, the year is generally written in numbers (1956, 2009, ...) but when you say it you need to literally say it as if it was a number, unlike in English which is expressed in "pairs".
So, in Spanish:
1975 ="mil / novecientos / setenta y cinco".
But in English:
1975 = "nineteen / seventy five"
Regards
Inma