There are likely still many gay an lesbian people still hiding their sexual orientation in the workplace today. The number in the early 2000s was probably a lot higher. In the workplace it shouldn't be anyone's business what orientation you are. Having to go out of your way to hide the orientation is not the solution though.
Gays and lesbians have hidden their sexual identity in the workplace for years and still do. Sadly we live in a status driven society where people are expected to conform to so called social norms. For many people it is much more advantageous to be a self identified heterosexual in terms of getting on and even been accepted at all in the workplace. This is the case even now in the earlier decades of the 2000's. People are always expected to be the same in terms of marrying someone of the opposite sex and have children and these attitudes have still not altered that much amongst some people even nowadays.