Here is a great dataset that will likely help you. It contains the top 1000 boy names and top 1000 girl names per year for babies born in the US from 1880 to 2009. Ranks and percents are also provided. Keep in mind that some names are shared between males and females, so a workaround could be to choose the sex w/ the highest percentage for conflict names.

The raw data originally comes from the Social Security Administration, but I am familiar with it because it comes with an R package as a sample dataset to play with.

UPDATE: the link I provided also has some R scripts to download the raw data from SSA and parse it. If you use these scripts, you can specify the dates and which states you want to pull the data from. Also, there is a script to grab the top X names for each sex. This could help you avoid shared name conflicts.