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          512        193 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         4425       1527 
1996         3593       1262 
1997         2337        797 
1998        23319       9830 
1999        14594       5599 
2000        40649      16877 
2001        41673      16253 
2002        32819      14665 
2003        61745      25591 
2004        48515      18613 
2005        86633      26614 
2006       112151      35804 
2007       206791      63329 
2008       127672      36296 
2009       103937      29187 
2010       120670      33482 
2011       181709      50240 
2012       168681      46666 
2013       262556      74456 
2014       653433     166601 
2015       760241     201635 
2016       579128     154452 
2017       608574     162479 
2018       406817     114014 
2019       932823     227447 
2020       705935     181176 
2021       919058     220923 
2022       687782     196680 
2023       619266     178201 
2024       140058      40116