andie you may be spotting a trend that has yet to show up in the stats, who knows?
The stats do allow for mixed feeding - the better surveys in the UK and worldwide differentiate between exclusive breastfeeding, predominantly bf, partial bf.
It is not a good thing to introduce formula early as a general principle, and while there is a cultural belief in some parts of the world that colostrum is not healthy, the mothers who believe this need better information from their healthcare providers about how great colostrum is Yes, they may go on to breastfeed afterwards, but it reduces their chances of maintaining breastfeeding.
Teaching women not to withhold colostrum is part of health education programmes in many parts of the world (examples here: www.ibfan.org/site2005/Pages/article.php?art_id=234&iui=1)
What can I say? The research shows that introduction of formula reduces the chances of a mother building up and maintaining breastfeeding. This may not be the case in individual instances, but it's not something to recommend, put it that way