Only junior matches are included in junior rankings. The career highs for singles and doubles refer to the era when there were separate rankings for both events (Aga being 14 in 2003). Since then singles and doubles have been combined into one ranking. Aga played enough tournaments to gain the number 1 ranking, winning 2 grand slams between 2005 (Wimbledon) and 2006 (Roland Garros)
Juniors used to get separate rankings for singles and doubles (Aga's early low rankings). These were subsequently abandoned and a combined ranking introduced consisting of the best 6 sets of points for singles plus 25% of the best 6 sets of dubs points in a 12 month rolling period. This gave Aga a top ranking later in her junior career.