Just did a quick collation out of 28 Prime Ministers since 1901 and thought I would share:
Forde, Francis Michael (ALP) 8 days Relinquished Position to New ALP Leader
Page, Earle Christmas Grafton (CP) 20 days Relinquished position to new UAP Leader
McEwen, John (CP) 23 days Relinquished Position to New Liberal Leader
Fadden, Arthur William (CP) 1 month, 9 days Defeated on Floor of House
Watson, John Christian (ALP) 3 months, 21 days Resigned Following House Amendment of Conciliation and Arbitration Bill and Governor-General?s Refusal To Dissolve House
Reid, George Houston (FT) 10 months, 18 days Resigned Following House Amendment of Address-In-Reply and Governor-General?s Refusal to Dissolve House
Cook, Joseph (LIB) 1 year, 2 months, 25 days Defeated at General Election
McMahon, William (LIB) 1 year, 8 months, 25 days Defeated at General Election
Holt, Harold Edward (LIB) 1 year, 10 months, 23 days Missing, Presumed Drowned
Scullin, James Henry (ALP) 2 years, 2 months, 16 days Defeated at General Election Following Party Split
Barton, Edmund (PROT) 2 years, 8 months, 24 days Appointed Justice of High Court
Rudd, Kevin Michael 2 years, 9 months, 12 days Deposed as Leader / Defeated at General Election
Whitlam, Edward Gough (ALP) 2 years, 11 months, 7 days Commission Terminated by Governor-General
Gillard, Julia Eileen (ALP) 3 years, 3 days Deposed as Leader
Gorton, John Grey (ALP) 3 years, 2 months Technically resigned as leader but effectively deposed
Note that Abbott, Anthony John (LIB) commenced his term on 18/9/13 and if not allowed to continue past Tuesday, will be up in the shortness of his term.
Forde, Francis Michael (ALP) 8 days Relinquished Position to New ALP Leader
Page, Earle Christmas Grafton (CP) 20 days Relinquished position to new UAP Leader
McEwen, John (CP) 23 days Relinquished Position to New Liberal Leader
Fadden, Arthur William (CP) 1 month, 9 days Defeated on Floor of House
Watson, John Christian (ALP) 3 months, 21 days Resigned Following House Amendment of Conciliation and Arbitration Bill and Governor-General?s Refusal To Dissolve House
Reid, George Houston (FT) 10 months, 18 days Resigned Following House Amendment of Address-In-Reply and Governor-General?s Refusal to Dissolve House
Cook, Joseph (LIB) 1 year, 2 months, 25 days Defeated at General Election
McMahon, William (LIB) 1 year, 8 months, 25 days Defeated at General Election
Holt, Harold Edward (LIB) 1 year, 10 months, 23 days Missing, Presumed Drowned
Scullin, James Henry (ALP) 2 years, 2 months, 16 days Defeated at General Election Following Party Split
Barton, Edmund (PROT) 2 years, 8 months, 24 days Appointed Justice of High Court
Rudd, Kevin Michael 2 years, 9 months, 12 days Deposed as Leader / Defeated at General Election
Whitlam, Edward Gough (ALP) 2 years, 11 months, 7 days Commission Terminated by Governor-General
Gillard, Julia Eileen (ALP) 3 years, 3 days Deposed as Leader
Gorton, John Grey (ALP) 3 years, 2 months Technically resigned as leader but effectively deposed
Note that Abbott, Anthony John (LIB) commenced his term on 18/9/13 and if not allowed to continue past Tuesday, will be up in the shortness of his term.