20 US Dollars Banknote (Twenty Dollars USA: 2006) Obverse & Reverse

20 US Dollars Banknote (Twenty Dollars USA: 2006) Obverse & Reverse.
United States twenty-dollar bill / 2006.
Issued: 2006
United States Banknotes: Pick New
Obverse: The seventh U.S. President Andrew Jackson.
Reverse: White House.
Color: Green-Gray-Yellow.
United States Currency - Value $ 20
Issued by: Federal Reserve Bank - Federal Reserve Note
Security Features: Micro-printing, Watermark, Optically Variable Ink, Security Thread, Security Fibers
Symbol: $ - USD - US$
Width: 156 mm
Height: 66,3 mm
Paper type: 75% cotton and 25% linen
Design date of series: October 9, 2003.
Years of printing: 1861-present.
Notes: 2003 Series - The current series of 20 dollar bills is released with light background shading in green and yellow, and no oval around Andrew Jackson's portrait (background images of eagles, etc. were also added to the front); the back is the same view of the White House, but without the oval around it. Ninety faint "20"s are scattered on the back in yellow as a "EURion constellation" to prevent photocopying. The first issue's series date is 2004 with Marin-Snow signatures. The bills were first printed in April 2003.
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The United States twenty-dollar bill ($20) is a denomination of U.S. currency. The seventh U.S. President (1829-37), Andrew Jackson has been featured on the front side of the bill since 1928, while the White House is featured on the reverse side. On April 20, 2016, it was announced that a new design, expected to be unveiled in 2020 (the 100th anniversary of the 19th Amendment), will have a portrait of Harriet Tubman on the front.
The twenty-dollar bill in the past was referred to as a "double-sawbuck" because it is twice the value of a ten-dollar bill, which was nicknamed a "sawbuck" due to the resemblance the Roman numeral for ten (X) bears to the legs of a sawbuck, although this usage had largely fallen out of favor by the 1980s.
As of December 2013, the average circulation life of a $20 bill is 7.9 years before it is replaced due to wear. Approximately 11% of all notes printed in 2009 were $20 bills. Twenty-dollar bills are delivered by Federal Reserve Banks in violet straps.

[@rwerner1143]

I have a 2006 series with a VERY dark green stamp. Is this unusual?