I know for sure that Snow White and The Seven Dwarfs took 3 years to make and Sleeping Beauty took around 8 years to make (I know that they began working with the movie in 1951 or 1952). I think Beauty and The Beast took 2 years to make (according to the trailer for the Platinum Edition release back in 2002) and The Princess and The Frog took 2 years to make
How about looking it up at wikipedia?
Snow White took three years (technically nearly four, since they started at the beginning of 1934 and the movie hit the theaters at the very end of december 1937).
With Cinderella, it's a little bit unclear when they actually started the movie...certainly only after the US Army left the Disney studios in 1945 and they could work freely again, but if they started immediatly after or needed first time to regroup is everybodies guess. It was a chaotic time back then. It was for sure already in production in 1948, when the voice of Cinderella was chosen, so my guess would be 3 to 4 years.
Sleeping Beauty took nearly the full decade to make. The work on the story boards started in 1951, the voices were recorded in 1952, the actual animation was done from 1953 to 1958 and the movie hit the theaters in 1959. Walt Disney kept saying that the production took "too long".
The Little Mermaid was actually a concept the studio already thought of in the 30th. When they restarted the idea, the actual production time was the for this time usual four years.
Beauty and the Beast on the other hand was rushed and finished in only two years.
Aladdin was started around the same time (though the pitch is from 1988), but was released one year later, so it's with three years nearer on the usual production time.
Pocahontas, as far as I know, also had the usual production time of around four years.
Same is true for Mulan, btw., Development started in 1994, the movie was released in 1998, so seven years is not correct.
The Disney Animation studios were reopened in 2006, so I guess PatF took three years.
And Tangled was apparently a nightmare in development and took 6 years.