Detailed Instructions: Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.
Problem:Passage: The third assessment report (TAR) prominently featured a graph labeled 'Millennial Northern Hemisphere temperature reconstruction' based on a 1999 paper by Michael E. Mann, Raymond S. Bradley and Malcolm K. Hughes (MBH99), which has been referred to as the 'hockey stick graph'. This graph extended the similar graph in Figure 3.20 from the IPCC Second Assessment Report of 1995, and differed from a schematic in the first assessment report that lacked temperature units, but appeared to depict larger global temperature variations over the past 1000 years, and higher temperatures during the Medieval Warm Period than the mid 20th century. The schematic was not an actual plot of data, and was based on a diagram of temperatures in central England, with temperatures increased on the basis of documentary evidence of Medieval vineyards in England. Even with this increase, the maximum it showed for the Medieval Warm Period did not reach temperatures recorded in central England in 2007. The MBH99 finding was supported by cited reconstructions by Jones et al. 1998, Pollack, Huang & Shen 1998, Crowley & Lowery 2000 and Briffa 2000, using differing data and methods. The Jones et al. and Briffa reconstructions were overlaid with the MBH99 reconstruction in Figure 2.21 of the IPCC report. Question: When was the paper published that the 'Millennial Northern Hemisphere temperature reconstruction' graph was based on?
Solution:
1999