I have measured the relative humidity as per my set up, and got steady readouts exactly in the 75% area as expected:
DHT22 Library Demo Requesting data...Got Data 25.50C 75.20% Integer-only reading: Temperature 25.5 C, Humidity 75.2 % RH Requesting data...Got Data 25.50C 75.20% Integer-only reading: Temperature 25.5 C, Humidity 75.2 % RH Requesting data...Got Data 25.50C 75.30% Integer-only reading: Temperature 25.5 C, Humidity 75.3 % RH Requesting data...Got Data 25.50C 75.40% Integer-only reading: Temperature 25.5 C, Humidity 75.4 % RH Requesting data...Got Data 25.60C 75.40% Integer-only reading: Temperature 25.6 C, Humidity 75.4 % RH Requesting data...Got Data 25.50C 75.40% Integer-only reading: Temperature 25.5 C, Humidity 75.4 % RH Requesting data...Got Data 25.60C 75.30% Integer-only reading: Temperature 25.6 C, Humidity 75.3 % RH Requesting data...Got Data 25.60C 75.30% Integer-only reading: Temperature 25.6 C, Humidity 75.3 % RH Requesting data...Got Data 25.60C 75.20% Integer-only reading: Temperature 25.6 C, Humidity 75.2 % RH Requesting data...Got Data 25.60C 75.10% Integer-only reading: Temperature 25.6 C, Humidity 75.1 % RH Requesting data...Got Data 25.60C 75.00% Integer-only reading: Temperature 25.6 C, Humidity 75.0 % RH Requesting data...Got Data 25.60C 75.00% Integer-only reading: Temperature 25.6 C, Humidity 75.0 % RH Requesting data...Got Data 25.60C 74.90% Integer-only reading: Temperature 25.6 C, Humidity 74.9 % RH Requesting data...Got Data 25.70C 74.80% Integer-only reading: Temperature 25.7 C, Humidity 74.8 % RH
So that means the DHT22 is accurate, good to know 
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