Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          532        200 
1992          936        367 
1993         1678        613 
1994         2342        845 
1995         4445       1534 
1996         3605       1266 
1997         2340        798 
1998        23370       9850 
1999        14657       5624 
2000        40955      17010 
2001        42064      16420 
2002        33364      14888 
2003        62498      25900 
2004        49149      18863 
2005        88052      27023 
2006       114047      36364 
2007       209375      64034 
2008       130805      37142 
2009       106467      29874 
2010       123478      34221 
2011       186797      51618 
2012       172688      47758 
2013       270113      76554 
2014       670130     170905 
2015       783164     207530 
2016       572609     153517 
2017       531131     147909 
2018       411760     115599 
2019       919495     224644 
2020       724607     186087 
2021       932690     224489 
2022       698800     199902 
2023       659954     189834 
2024            4          0