According to the data something happended around 18-20. Jan 2015
Sudden drop in Ch1,2,3,5 from 20. Jan

Drift 2015								
Lamp 2 
2015	94	0.523	0.39	0.065	0.17	0.89	0.97
2015	134	0.471	0.35	0.055	0.15	0.83	1.00
2015	156	0.469	0.35	0.057	0.16	0.87	0.97

Lamp 3
2015	94	0.645	0.505	0.075	0.185	1.058	1.217
2015	134	0.578	0.443	0.064	0.174	1.028	1.229
2015	156	0.599	0.462	0.066	0.181	1.064	1.222