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         1669        610 
1994         2333        842 
1995         4425       1527 
1996         3602       1265 
1997         2340        798 
1998        23334       9837 
1999        14615       5608 
2000        40729      16914 
2001        41798      16305 
2002        32938      14711 
2003        61975      25688 
2004        48658      18671 
2005        86992      26719 
2006       112673      35957 
2007       207667      63566 
2008       128571      36537 
2009       104540      29353 
2010       121509      33704 
2011       183103      50620 
2012       169752      46958 
2013       264802      75089 
2014       660645     168445 
2015       772864     204769 
2016       577792     154200 
2017       588683     157800 
2018       406604     114068 
2019       928390     226627 
2020       712421     182853 
2021       924742     222417 
2022       692053     197860 
2023       628187     180776 
2024        97859      28540