http://en.wikipedia.org/wiki/Android_version_history
Version history by API level 2.1 Android 1.0 (API level 1) 2.2 Android 1.1 (API level 2) 2.3 Android 1.5 Cupcake (API level 3) 2.4 Android 1.6 Donut (API level 4) 2.5 Android 2.0 Eclair (API level 5) 2.6 Android 2.0.1 Eclair (API level 6) 2.7 Android 2.1 Eclair (API level 7) 2.8 Android 2.2–2.2.3 Froyo (API level 8) 2.9 Android 2.3–2.3.2 Gingerbread (API level 9) 2.10 Android 2.3.3–2.3.7 Gingerbread (API level 10) 2.11 Android 3.0 Honeycomb (API level 11) 2.12 Android 3.1 Honeycomb (API level 12) 2.13 Android 3.2 Honeycomb (API level 13) 2.14 Android 4.0–4.0.2 Ice Cream Sandwich (API level 14) 2.15 Android 4.0.3–4.0.4 Ice Cream Sandwich (API level 15) 2.16 Android 4.1 Jelly Bean (API level 16) 2.17 Android 4.2 Jelly Bean (API level 17) 2.18 Android 4.3 Jelly Bean (API level 18) 2.19 Android 4.4 KitKat (API level 19) 2.20 Android 4.4 KitKat with wearable extensions (API level 20) 2.21 Android 5.0 Lollipop (API level 21)