No offence, but you clearly know nothing at all about the Philippines.
Not only is it predominantly Catholic, but many other 'Christian' groups are active, complete with missionaries going door to door, including Methodists, Baptists, LDS.
There are major reasons for this, and if you are going to compare statistics you need to know and understand them first. It is a country that has a Catholic tradition - the result is large, close, familes with a lot of children, endemic corruption and severe poverty. 40% of the population earns less than $2 a day. It is decidedly 3rd world. Most do not complete a High School education, and those who do would still struggle to pass a test given to 11 year olds in the West.
The people are traditionally hospitible and friendly, trusting, modest and likely to follow direction.
In other words, they are ripe for conversion. They need the (false) hope these religions peddle, are highly uneducated so only need to trust the 'teacher'; they do not need to understand any of the actual doctrines to believe, perfect for JW's.
Jw's do well in countries like these as do other faiths.
The Catholic Church is going through a rough patch, with scandal after scandal being reported in the press. They also oppose divorce and any forms of contraception while most of the population hopes for both to be available in the future.
So, before comparing 2 sets of stats and trying to work out if this is caused by the door to door work you need to factor in some basic facts about the place first.
P.S. It's not nit-picking when your ignorance is the size of an elephant.