How many times was the viewer target group 0.63?
create table table_2639433_4 (market_share__target_group_14_49_ varchar, viewers__in_millions_target_group_14_49_ varchar, PRIMARY KEY (market_share__target_group_14_49_))
select count(market_share__target_group_14_49_) from table_2639433_4 where viewers__in_millions_target_group_14_49_ = "0.63"