As of the census of 2000, 750,097 people, 286,098 households, and 197,693 families resided in the county.  The population density was 1,553 people per square mile (599/km²). The 297,434 housing units averaged 238 units/km² (616 units/sq mi).  The Race (United States Census) of the county was 86.46% White, 7.46% Black or African American, 0.11% Native American, 4.02% Asian, 0.03% Pacific Islander, 0.75% from other races, and 1.16% from two or more races.  About 2.04% of the population were Hispanic or Latino of any race, 17.5% were of German people, 16.7% Irish people, 14.3% Italian people, 6.5% English people, and 5.0% Polish people ancestry according to 2000 United States Census. Around 90.5% spoke English language, 2.0% Spanish language, 1.1% korean language, and 1.0% Italian language as their first language.  Historically, much of western Montgomery County is part of the Pennsylvania Dutch Country, with a great many descendants of German language-speaking settlers from the 18th century.
Question: Which ancestries had between 15% and 20%?
Answer: German | Irish